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[SCEV] Add predicate in SolveLinEq to ensure B is a multiple of A. #108777

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Merged
merged 10 commits into from
Sep 28, 2024
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[SCEV] Add predicate in SolveLinEq to ensure B is a multiple of A. #108777

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c91b942
[SCEV] Add predicate in SolveLinEq to ensure B is a multiple of A.
fhahn Sep 15, 2024
2832a8a
Merge remote-tracking branch 'origin/main' into scev-align-predicate
fhahn Sep 26, 2024
fcf36c4
!fixup Address latest comments, thanks!
fhahn Sep 26, 2024
f23bddc
Merge remote-tracking branch 'origin/main' into scev-align-predicate
fhahn Sep 26, 2024
c312060
!fixup update and assert.
fhahn Sep 26, 2024
d6522f9
!fixup use APInt::getOneBitSet, thanks!
fhahn Sep 26, 2024
7624c7d
Merge remote-tracking branch 'origin/main' into scev-align-predicate
fhahn Sep 27, 2024
f648176
Merge remote-tracking branch 'origin/main' into scev-align-predicate
fhahn Sep 27, 2024
e36de7d
!fixup replace assertion with check
fhahn Sep 27, 2024
ee755af
!fixup update thumb test
fhahn Sep 28, 2024
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30 changes: 24 additions & 6 deletions llvm/lib/Analysis/ScalarEvolution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10129,8 +10129,11 @@ const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const {
/// A and B isn't important.
///
/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
ScalarEvolution &SE) {
static const SCEV *
SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
SmallPtrSetImpl<const SCEVPredicate *> *Predicates,

ScalarEvolution &SE) {
uint32_t BW = A.getBitWidth();
assert(BW == SE.getTypeSizeInBits(B->getType()));
assert(A != 0 && "A must be non-zero.");
Expand All @@ -10146,8 +10149,22 @@ static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B,
//
// B is divisible by D if and only if the multiplicity of prime factor 2 for B
// is not less than multiplicity of this prime factor for D.
if (SE.getMinTrailingZeros(B) < Mult2)
return SE.getCouldNotCompute();
if (SE.getMinTrailingZeros(B) < Mult2) {
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Should we maybe try to prove that (urem B, A) == 0 before resorting to the predicate?

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IIUC that check shouldn't be true, otherwise we are missing some logic in getMinTrailingZeros? Added an assert that the check isn't true.

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With the reframing of urem (B, 1 << Mult2) == 0, I agree with your comment, but I think we could reasonable see divergence with the original urem(B,A) check. Those are just different enough.

My suggestion is basically, can we prove the original fact without using the trailing bits proof strategy? Said differently. what if D = gcd(A, N) is something like 3^M?

Hm, though now I see that the multiplicative inverse code below would need updated too. I'd missed that originally.

(Totally fine to move forward here, this is purely a possible followup.)

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I stand corrected, the assertion actually uncovered a case where getMinTrailingZeros returns a worse result and I think catching this in getMinTrailingZeros would require matching a specific pattern (https://alive2.llvm.org/ce/z/t3A5X2)

I updated the code to check if the URem is zero if the trailing bits check failed, as we need to build the expression there already. Test is in llvm/test/Analysis/ScalarEvolution/trip-count-urem.ll

// Check if we can prove there's no remainder using URem.
const SCEV *URem =
SE.getURemExpr(B, SE.getConstant(APInt::getOneBitSet(BW, Mult2)));
const SCEV *Zero = SE.getZero(B->getType());
if (!SE.isKnownPredicate(CmpInst::ICMP_EQ, URem, Zero)) {
// Try to add a predicate ensuring B is a multiple of 1 << Mult2.
if (!Predicates)
return SE.getCouldNotCompute();

// Avoid adding a predicate that is known to be false.
if (SE.isKnownPredicate(CmpInst::ICMP_NE, URem, Zero))
return SE.getCouldNotCompute();
Predicates->insert(SE.getEqualPredicate(URem, Zero));
}
}

// 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
// modulo (N / D).
Expand Down Expand Up @@ -10577,8 +10594,9 @@ ScalarEvolution::ExitLimit ScalarEvolution::howFarToZero(const SCEV *V,
// Solve the general equation.
if (!StepC || StepC->getValue()->isZero())
return getCouldNotCompute();
const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
getNegativeSCEV(Start), *this);
const SCEV *E = SolveLinEquationWithOverflow(
StepC->getAPInt(), getNegativeSCEV(Start),
AllowPredicates ? &Predicates : nullptr, *this);

const SCEV *M = E;
if (E != getCouldNotCompute()) {
Expand Down
101 changes: 101 additions & 0 deletions llvm/test/Analysis/ScalarEvolution/ne-overflow.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,15 @@ define void @test_well_defined_infinite_st(i32 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i32 2147483647
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
;
entry:
br label %for.body
Expand All @@ -79,6 +88,15 @@ define void @test_well_defined_infinite_ld(i32 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i32 2147483647
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
;
entry:
br label %for.body
Expand All @@ -100,6 +118,15 @@ define void @test_no_mustprogress(i32 %N) {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i32 2147483647
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
;
entry:
br label %for.body
Expand Down Expand Up @@ -187,6 +214,15 @@ define void @test_abnormal_exit(i32 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i32 2147483647
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
;
entry:
br label %for.body
Expand All @@ -209,10 +245,24 @@ define void @test_other_exit(i32 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for for.body: i32 9
; CHECK-NEXT: exit count for for.latch: ***COULDNOTCOMPUTE***
; CHECK-NEXT: predicated exit count for for.latch: ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-EMPTY:
; CHECK-NEXT: Loop %for.body: constant max backedge-taken count is i32 9
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is i32 9
; CHECK-NEXT: symbolic max exit count for for.body: i32 9
; CHECK-NEXT: symbolic max exit count for for.latch: ***COULDNOTCOMPUTE***
; CHECK-NEXT: predicated symbolic max exit count for for.latch: ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-EMPTY:
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (9 umin ((-2 + %N) /u 2))
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is (9 umin ((-2 + %N) /u 2))
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i32 %N to i1) to i32) == 0
;
entry:
br label %for.body
Expand Down Expand Up @@ -267,6 +317,18 @@ define void @test_sext(i64 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i64 9223372036854775807
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
;
entry:
br label %for.body
Expand All @@ -288,6 +350,21 @@ define void @test_zext_of_sext(i64 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i64 9223372036854775807
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %N to i1) to i64) == 0
;
entry:
br label %for.body
Expand All @@ -310,6 +387,18 @@ define void @test_zext_offset(i64 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-21 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i64 9223372036854775807
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-21 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
;
entry:
br label %for.body
Expand All @@ -332,6 +421,18 @@ define void @test_sext_offset(i64 %N) mustprogress {
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-21 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated constant max backedge-taken count is i64 9223372036854775807
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
; CHECK-NEXT: Loop %for.body: Predicated symbolic max backedge-taken count is ((-21 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: Equal predicate: (zext i1 (true + (trunc i64 %N to i1)) to i64) == 0
;
entry:
br label %for.body
Expand Down
32 changes: 32 additions & 0 deletions llvm/test/Analysis/ScalarEvolution/predicated-max-backedge-taken-count-guard-info.ll
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Expand Up @@ -7,6 +7,15 @@ define i32 @ptr_induction_ult(ptr %a, ptr %b) {
; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (((-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) /u 4)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i2 ((trunc i64 (ptrtoint ptr %b to i64) to i2) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i2))) to i64) == 0
; CHECK-NEXT: Loop %loop: Predicated constant max backedge-taken count is i64 4611686018427387903
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i2 ((trunc i64 (ptrtoint ptr %b to i64) to i2) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i2))) to i64) == 0
; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is (((-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) /u 4)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i2 ((trunc i64 (ptrtoint ptr %b to i64) to i2) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i2))) to i64) == 0
;
entry:
%cmp.6 = icmp ult ptr %a, %b
Expand All @@ -28,6 +37,15 @@ define i32 @ptr_induction_ult_3_step_6(ptr %a, ptr %b) {
; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (((3074457345618258603 * (ptrtoint ptr %b to i64)) + (-3074457345618258603 * (ptrtoint ptr %a to i64))) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 ((-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) to i1) to i64) == 0
; CHECK-NEXT: Loop %loop: Predicated constant max backedge-taken count is i64 9223372036854775807
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 ((-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) to i1) to i64) == 0
; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is (((3074457345618258603 * (ptrtoint ptr %b to i64)) + (-3074457345618258603 * (ptrtoint ptr %a to i64))) /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 ((-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) to i1) to i64) == 0
;
entry:
%cmp.6 = icmp ult ptr %a, %b
Expand Down Expand Up @@ -74,10 +92,24 @@ define void @ptr_induction_early_exit_eq_1(ptr %a, ptr %b, ptr %c) {
; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for loop.inc: ***COULDNOTCOMPUTE***
; CHECK-NEXT: predicated exit count for loop.inc: ((-8 + (-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) /u 8)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i3 ((trunc i64 (ptrtoint ptr %b to i64) to i3) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i3))) to i64) == 0
; CHECK-EMPTY:
; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: symbolic max exit count for loop.inc: ***COULDNOTCOMPUTE***
; CHECK-NEXT: predicated symbolic max exit count for loop.inc: ((-8 + (-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) /u 8)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i3 ((trunc i64 (ptrtoint ptr %b to i64) to i3) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i3))) to i64) == 0
; CHECK-EMPTY:
; CHECK-NEXT: Loop %loop: Predicated constant max backedge-taken count is i64 2305843009213693951
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i3 ((trunc i64 (ptrtoint ptr %b to i64) to i3) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i3))) to i64) == 0
; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is ((-8 + (-1 * (ptrtoint ptr %a to i64)) + (ptrtoint ptr %b to i64)) /u 8)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i3 ((trunc i64 (ptrtoint ptr %b to i64) to i3) + (-1 * (trunc i64 (ptrtoint ptr %a to i64) to i3))) to i64) == 0
;
entry:
%cmp = icmp eq ptr %a, %b
Expand Down
7 changes: 4 additions & 3 deletions llvm/test/Analysis/ScalarEvolution/trip-count-urem.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,10 @@ declare void @foo()
define void @test_trip_count_expr_contains_urem(i32 %N) {
; CHECK-LABEL: 'test_trip_count_expr_contains_urem'
; CHECK-NEXT: Determining loop execution counts for: @test_trip_count_expr_contains_urem
; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
; CHECK-NEXT: Loop %loop: backedge-taken count is ((1 + (-1 * (zext i4 (1 + (trunc i32 %N to i4)) to i32))<nsw> + %N) /u 16)
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 268435455
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((1 + (-1 * (zext i4 (1 + (trunc i32 %N to i4)) to i32))<nsw> + %N) /u 16)
; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%n.rnd.up = add i32 %N, 1
Expand Down
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